Development of a Cold Gas Propulsion System for the ... - SSL - MIT

7 Ongoing and Future Work
There are three main thrusts of ongoing and future work for the TALARIS CGSE. The first is validation
testing of the CGSE, which couples further hardware testing with tests of GNC algorithms. The second is
more complete characterization of the existing CGSE system’s capabilities as well as the development of
best practices for its operation. The third is making changes to improve the TALARIS spacecraft emulator
propulsion system. This work could range in scope from relatively small changes, like swapping out parts
in the CGSE, to a full redesign of the system to utilize hydrogen peroxide as a monopropellant.
7.1 Validation Testing
The single-stream component tests as well as the static characterization tests of the CGSE flight system
had all been performed for verification; that is, to ensure that the CGSE met the derived technical
performance requirements laid out in section 3.1.4. The next step was to check that these requirements
added up to a system that performed the original top-level goals for which it was designed, and the way
to accomplish this was through validation testing. As the NASA Systems Engineering Handbook says,
“Validation testing is conducted under realistic conditions (or simulated conditions) on any end product
to determine the effectiveness and suitability of the product for use in mission operations by typical
users and to evaluate the results of such tests” [60].
For the TALARIS CGSE, validation means proving that it can propel and control the vehicle through all
phases of a hover hop. However, it would be a very large leap to go directly from static characterization
testing to unrestrained free flight, and due to its limited budget and rigorous safety constraints, the
TALARIS project cannot tolerate a crash or other destructive failure. Thus, an incremental validation
testing program was developed. It was planned that in the first few tests, the hopper would have some
of its degrees of freedom (DOFs) restricted so that it could only move in certain ways. Closed-loop CGSE
control could progressively be applied to more and more degrees of freedom, with a greater chance of
catching any major problems early in a more controlled environment, until enough confidence had been
developed in both the hardware and the software to permit 6-DOF free flight hopping. The execution of
this plan is in progress at the time of writing this thesis.
7.1.1 Horizontal Traverse and Roll Testing
When validation testing for the TALARIS CGSE began, the EDF weight-relief propulsion system was being
upgraded and was not available for flight. Thus, the first CGSE validation tests focused on the horizontal
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